The present invention relates to a security system having a deactivatable security tag that is applied to an article normally located for sale in a retail establishment. More particularly, the subject invention relates to a security tag for use in a security system wherein the tag includes a coil having a resonant frequency and that is formed of a unique composition of materials that incorporates a conductive material therein. The invention further includes a neutralizing device that generates a high energy magnetic field for deactivating the coil of the security tag.
Electronic security systems that utilize a security tag having a resonant circuit of a predetermined tuned frequency are in common use and are generally employed for the purpose of preventing theft of goods in a retail establishment. Examples of security tags known heretofore that incorporate a resonant tag circuit therein are illustrated in the following United States patents and represent the relevant prior art known to the applicants: LICHTBLAU, U.S. Pat. Nos. 3,810,147; LICHTBLAU, 3,967,161; LICHTBLAU, 4,567,473; LAMOND et al, 4,835,524 and ANDREWS, 4,920,335.
The security tags as described in the prior known systems are tuned to a specific frequency such that a resonant condition resulting from an RF field is sensed when the articles containing the tag pass through a controlled area. In some of the prior known devices, the security tag is deactivated by a paste-over applied thereto in the form of a metalized sticker that prevents the resonant circuit from causing an alarm when passed through an exit scanning area. In a more recent form of security tag, the coil that defines the circuit of the tag is provided with a fused element that when subjected to a swept frequency of higher energy than that employed for detection, the fusible link of the resonant circuit is destroyed to deactivate the tuned circuit so that detection is no longer possible. In this circumstance, a deactivating device which is located at a checkout area in a retail establishment is operable to produce the high energy field for deactivating the tuned circuit of the security tag. Thereafter, when a customer with a deactivated tag applied to an article as purchased passes through an exit area, the resonant circuit of the security tag which has been deactivated will not resonate a signal for causing an alarm to be sounded when swept by a predetermined frequency.
The heretofore known security tags have normally included a spiral conductor that functions as an inductor of the resonant circuit of the tag and is usually comprised of a conductive material such as aluminum or the like. Aluminum may be etched in a dielectric substrate in the spiral strip, a conductive plate which defines a capacitor usually being located in series with the inductive spiral strip. Although the conductive aluminum etch material has been found to be satisfactory for the purposes intended, the spiral aluminum strip is limited in the manner of use thereof and must be applied to merchandise as sold in a retail establishment by the adhering thereof directly onto the article. This procedure in not only labor intensive, but is subject to improper removal. Further, since the coil that defines the prior known security tag is formed by a special process and with special kinds of equipment, these security tags must be applied to the articles in the retail establishment separately from other kinds of identifying labels normally attached to said articles, and as a result are usually discernable by casual observance.
As will be described hereinafter, the present invention not only includes a security tag that has a resonant frequency coil incorporated therein, but includes a tag formed of composition materials that are easily printable on various kinds of substrates, such as film, paper or cloth that are easily attachable to a retail store article. Further, as will be described, a unique neutralizing system is employed in the subject invention to deactivate the security tag as the article to which it is attached passes through a controlled checkout area.